I've found a reliable crash with EXC_BAD_ACCESS while implementing a cache on my app. I've recreated the situation in a new project in about ~50 lines of code with 2 pods (Alamofire, HanekeSwift), and it crashes every time.
All I am doing is in my ViewController, calling a cache get:
CachingManager.sharedInstance.fetchAllThings({
result in
// result should be an array of objects
print(result)
})
and the CachingManager's fetchAllThings method is:
func fetchAllThings(completion: ([AnyObject] -> Void)?) {
let fetcher = CustomFetcher<JSON>(key: "HELLO")
fetcher.fetch(failure: {
error in
print(error)
}, success: {
json in
completion?(json.array)
})
}
Now, the CustomFetcher found above is implemented as such:
override func fetch(failure fail: ((NSError?) -> ()), success succeed: (JSON) -> ()) {
let endpoint = "www.google.com"
Alamofire.request(.GET, endpoint, parameters: nil, encoding: .URL, headers: nil)
.responseJSON {
(data) -> Void in
self.onReceiveData(data.data!, failure: fail, success: succeed)
}
}
private func onReceiveData(data: NSData, failure: ((NSError?) -> ()), success: (JSON) -> ()) {
success(JSON.Array(["HI"])) <--- CRASH HAPPENS HERE
}
I get an EXC_BAD_ACCESS when trying to run the success block in my onReceiveData.
Am I doing something wrong? Is this a Swift issue? Is this an issue with the pods I'm using?
For reference, linked is a project with the code above that will crash on launch every time if that helps anyone debug this.
Project on GitHub
Seems like the use of a Custom fetcher is not that clear in the Haneke docs. With the above fetchAllThings method, I was trying to fetch directly from the CustomFetcher, which was causing the bad access (that is not it's intended use, I am guessing). The correct way to use a fetcher with a JSON cache is:
func fetchAllThings(completion: ([AnyObject] -> Void)?) {
let fetcher = CustomFetcher<JSON>(key: "HELLO")
let cache = Shared.JSONCache
cache.fetch(fetcher: fetcher, formatName: "original", failure: {
error in
print(error)
}, success: {
json in
completion?(json.array)
})
}
The key here is that I am now using the library's cache object to invoke the Fetcher.
I hope this helps someone!
Related
My promise chain is broken (maybe deallocated) before it's resolved.
This happens (so far ONLY) when I make Alamofire request fail due to host trust evaluation -> forcing evaluation to fail which results in -999 cancelled etc).
Setup is rather simple:
APIRequest:
func start(_ onSuccess:#escaping SuccessBlock, onError:#escaping ErrorBlock) {
do {
try executeRequest { dataResponse in
self.onSuccess(dataResponse)
}
} catch {
self.onError(error)
}
}
where executeRequest() is:
self.manager.request(request).responseJSON(queue: self.queue) { (response) in
completion(response)
}
Then, there is PromiseKit wrapper defined as APIRequest extension:
(This wrapper callbacks are called correctly in either case)
func start() -> Promise<APIResponse> {
return Promise<APIResponse> { resolver in
self.start({ response in
resolver.fulfill(response)
}) { error in
resolver.reject(error)
}
}
}
And finally, unit test calling the start promise (extension):
( flow never reaches this place in case of Alamofire failing )
request.start().done { response in
}.catch { error in
// not called if request failed
}
Outcome: if request fails -> the extension promise wrapper (catch) block is called, but it's not propagated back to UnitTest promise block.
Simply replacing Alamofire request with mock implementation (which triggers some other error( makes all setup work as expected (Unit Test completes with catch block being called etc) ex:
DispatchQueue.global(qos: .default).asyncAfter(deadline: .now() + 2) {
let result = Alamofire.Result { () -> Any in
return try JSONSerialization.data(withJSONObject: [:], options: .fragmentsAllowed)
}
completion(DataResponse<Any>(request: nil, response: nil, data: nil, result: result))
}
Is this something to do with Alamofire? I don't really see how else to handle the promises there ( they shouldn't deallocate anyways... Or is this bug in PromiseKit? Alamofire? I yet have to test this in the app itself ( maybe it's Unit test issue ... )
Looking at related issues -> i'm definitely resolving promises (fulfilling / rejecting) for any flow path.
I don't see how Alamofire request is different from DispatchAsync (where the latter works as expected).
I was only 10 mins short of finding the answer... Problem is also described here:
https://github.com/mxcl/PromiseKit/issues/686
Issue is that '-999 cancelled' error is not treated as 'Error' by PromiseKit. Solution is to use "catch(policy: .allErrors)" - then catch block is called as expected.
func start(_ onSuccess:#escaping SuccessBlock, onError:#escaping ErrorBlock) {
do {
try executeRequest { dataResponse in
onSuccess(dataResponse)
}
} catch {
onError(error)
}
}
You are using self.onSuccess that means its not function parameter block but instance block thats why its not going back to block from you are calling start.
I've been trying since the morning but I didnt achieve what I wanted.
I tried DispatchQueue.main.async and completion block but my "Submit" button in the UI still freezes waiting for the data to be returned from the server. This is my code:
func createData(request:Crudpb_CreateRequest, with completion: #escaping (String) -> Void) throws {
DispatchQueue.main.async {
self.response = try! self.client.create(request) // <---- How to handle error for this server call when the server is not available or is down?
completion(self.response.result)
}
}
I just noticed Im calling the 1st method from the following which is a Synchronous Unary which might be the reason behind the problem. But again I dont know how to call the second function in the fallowing:
/// Synchronous. Unary.
internal func create(_ request: Crudpb_CreateRequest, metadata customMetadata: Metadata) throws -> Crudpb_CreateResponse {
return try Crudpb_CrudServiceCreateCallBase(channel)
.run(request: request, metadata: customMetadata)
}
/// Asynchronous. Unary.
#discardableResult
internal func create(_ request: Crudpb_CreateRequest, metadata customMetadata: Metadata, completion: #escaping (Crudpb_CreateResponse?, CallResult) -> Void) throws -> Crudpb_CrudServiceCreateCall {
return try Crudpb_CrudServiceCreateCallBase(channel)
.start(request: request, metadata: customMetadata, completion: completion)
}
Server Side Code:
func (*server) Create(ctx context.Context, req *crudpb.CreateRequest) (*crudpb.CreateResponse, error) {
var result string
firstName := req.GetAccount().GetFirstName()
lastName := req.GetAccount().GetLastName()
// id := gocql.TimeUUID()
fmt.Println("Triggered CREATE function on Go Server " + firstName + " " + lastName + "! Yayy!")
result = fmt.Sprintf("id for %s %s : %s", firstName, lastName, strconv.Itoa(rand.Intn(100)))
return &crudpb.CreateResponse{
Result: result,
}, nil
I need this app / submit button not to freeze while it fetches result from server.
Please help.
You are still performing work on the main thread.. async only makes the createData() method to return before the task is completed.. but the task will still be processed at some time in the main thread and during this time your application will become unresponsive.. try using a global queue instead.. to keep your main thread clean..
Dont forget to perform all your UI work on the main thread after getting your response.
Use the asynchronous function instead and call the completion block inside create function's completion.
func createData(request:Crudpb_CreateRequest, with completion: #escaping (String) -> Void) throws {
try! self.client.create(request) { (response: Crudpb_CreateResponse?, result: CallResult) in
DispatchQueue.main.async {
// This is assuming your completion involves UI operations. Otherwise there is no need for this async call.
let stringOutput = String(data: result.resultData!, encoding: String.Encoding.utf8))
completion(stringOutput)
}
}
}
Remove DispatchQueue.main.async block from the createData method
func createData(request:Crudpb_CreateRequest, with completion: #escaping (String) -> Void) throws {
self.response = try! self.client.create(request)
completion(self.response.result)
}
Use main queue only where you update the UI from the api response
myobj.createData(request: request, with: { string in
print(string)//background thread
DispatchQueue.main.async {
self.label.text = sting//main thread
}
})
The UI freeze because you are doing too much work on the main thread. You should find out what function blocks the main thread.
The instruments time profiler is an easy way to see which function is spending too much time.
I am now making a UITextField with AutoComplete that users will get a place name and zip code list after they have tapped one or some letters.
I got an Autocomplelt (https://github.com/cjcoax/Autocomplete) and there is a delegate function:
func autoCompleteItemsForSearchTerm(term: String) -> [AutocompletableOption]
I have to send a http request with term to server and wait for a json response as return.
For network connenction, I used Moya lib and its Method like:
CredentialProvider.request(.Autocomplete(term, 10)) { (result) -> () in }
Now, my question is: How can I make a return value after getting the response from server?
Thanks
Declare a function with completion block:
class func authenticateUser(userName:String?,password:String?,completionHandler: (response:NSDictionary?) -> (Void)) ->Void
{
completionHandler(response: nil(or)dict)
}
Call a function :
authenticateUser(emailId, password: password, completionHandler: { (response) in
print(response)
})
This Is how i get the instance of my network client:
let networkClient = DBNetworkClient(baseURL: NSURL(string: "http://mysite.pl/api"))
I also have one method:
func citiesWithParameters(parameters: [String: String], completionBlock: DBSearchOptionHandler) {
GET("cities", parameters: parameters, success: { operation, response in
if let error = NSError(response: response) {
completionBlock([], error)
} else {
let cities = DBCity.parseCitiesWithDictionary(response as! NSDictionary)
completionBlock(cities, nil)
}
}) { operation, error in
completionBlock([], error)
}
}
This is how I call this method:
networkClient.citiesWithParameters(parameters, completionBlock: { cities, error in
//do sth
})
This way I pass some parameters, and get the REAL response from server. I would like to mock THAT response when I ask for this. How to do this?
func testCities() {
let mockNetworkClient = OCMockObject.mockForClass(DBNetworkClient.classForCoder())
//what should I perform here to be able to do sth like this:
let expectation = expectationWithDescription("")
mockNetworkClient.citiesWithParameters(["a": "b"]) { cities, error in
expectation.fulfill()
XCTAssertNotNil(cities)
XCTAssertNil(error) //since I know what is the response, because I mocked this
}
waitForExpectationsWithTimeout(10, handler: nil)
}
And this is how my method GET is defined within DBNetworkClient:
override func GET(URLString: String!, parameters: AnyObject!, success: ((AFHTTPRequestOperation!, AnyObject!) -> Void)!, failure: ((AFHTTPRequestOperation!, NSError!) -> Void)!) -> AFHTTPRequestOperation! {
return super.GET(URLString, parameters: parameters, success: { (operation, response) in
print("GET \(operation.request.URL)")
print("GET \(response)")
success(operation, response)
}, failure: { (operation, error) in
print("GET \(operation.request.URL)")
print("GET \(operation.responseObject)")
failure(operation, error)
})
}
Once I will be able I will award 50 bounty for the one, who help me do this.
Writing mock tests for AFNetworking is unfortunetaly not helpful. It is not working for me.
I do not have experience with Alamofire therefore I don't know where is declared your GET method but you should definitely stub this method instead of citiesWithParameters.
For example if it's declared in your DBNetworkClient:
func testCities()
{
//1
class DBNetworkClientMocked: DBNetworkClient
{
//2
override func GET(URLString: String!, parameters: AnyObject!, success: ((AFHTTPRequestOperation!, AnyObject!) -> Void)!, failure: ((AFHTTPRequestOperation!, NSError!) -> Void)!) -> AFHTTPRequestOperation! {
//3
success(nil, ["San Francisco", "London", "Sofia"])
}
}
//4
let sut = DBNetworkClientMocked()
sut.citiesWithParameters(["a":"b"]) { cities, error in
//5
XCTAssertNotNil(cities)
XCTAssertNil(error)
}
}
So what happens here:
You define class that is children to DBNetworkClient, therefore making a 'Mock' for it as described in article you posted. In that class we will override only methods that we want to change(stub) and leave others unchanged. This was previously done with OCMock and was called Partial Mock.
Now you stub it's GET method in order to return specific data, not actual data from the server
Here you can define what to return your stubbed server. It can be success failure etc.
Now after we are ready with mocks and stubs, we create so called Subject Under Test(sut). Please note that if DBNetworkClient has specific constructor you must call this constructor instead of default one - ().
We execute method that we want to test. Inside it's callback we put all our assertions.
So far so good. However if GET method is part of Alamofire you need to use a technique called Dependency Injection(you could google it for more info).
So if GET is declared inside another class and is only referenced in citiesWithParameters, how we can stub it? Let's look at this:
//1
class DBNetworkClient
{
//2
func citiesWithParameters(parameters: [String: String], networkWorker: Alamofire = Alamofire(), completionBlock: DBSearchOptionHandler) {
//3
networkWorker.GET("cities", parameters: parameters, success: { operation, response in
if let error = NSError(response: response) {
completionBlock([], error)
} else {
let cities = DBCity.parseCitiesWithDictionary(response as! NSDictionary)
completionBlock(cities, nil)
}
}) { operation, error in
completionBlock([], error)
}
}
}
func testCities()
{
//4
class AlamofireMock: Alamofire
{
override func GET(URLString: String!, parameters: AnyObject!, success: ((AFHTTPRequestOperation!, AnyObject!) -> Void)!, failure: ((AFHTTPRequestOperation!, NSError!) -> Void)!) -> AFHTTPRequestOperation! {
success(nil, ["San Francisco", "London", "Sofia"])
}
}
//5
let sut = DBNetworkClient()
sut.citiesWithParameters(["a":"b"], networkWorker: AlamofireMock()) { cities, error in
//6
XCTAssertNotNil(cities)
XCTAssertNil(error)
}
}
First we have to slightly change our citiesWithParameters to receive one more parameter. This parameter is our dependency injection. It is the object that have GET method. In real life example it will be better this to be only protocol as citiesWithParameters doesn't have to know anything more than this object is capable of making requests.
I've set networkWorker parameter a default value, otherwise you need to change all your call to citiesWithParameters to fulfill new parameters requirement.
We leave all the implementation the same, just now we call our injected object GET method
Now back in tests, we will mock Alamofire this time. We made exactly the same thing as in previous example, just this time mocked class is Alamofire instead of DBNetworkClient
When we call citiesWithParameters we pass our mocked object as networkWorker. This way our stubbed GET method will be called and we will get our expected data from 'fake' server.
Our assertions are kept the same
Please note that those two examples do not use OCMock, instead they rely entirely on Swift power! OCMock is a wonderful tool that we used in great dynamic language - Objective-C. However on Swift dynamism and reflection are almost entirely missing. Thats why even on official OCMock page we had following statement:
Will there be a mock framework for Swift written in Swift? Maybe. As
of now it doesn't look too likely, though, because mock frameworks
depend heavily on access to the language runtime, and Swift does not
seem to provide any.
The thing that is missing with in both implementations provided is verifying GET method is called. I'll leave it like this because that was not original question about, and you can easily implement it with a boolean value declared in mocked class.
One more important thing is that I assume GET method in Alamofire is instance method, not a class method. If that's not true you can declare new method inside DBNetworkClient which simply calls Alamofire.GET and use that method inside citiesWithParameters. Then you can stub this method as in first example and everything will be fine.
Please help me to solve this problem - after a lot of (not so efficent...) search I can't do this alone.
I have the following methods:
showLoadingAnimation()
to show the loading animation while background tasks are running
hideLoadingAnimation()
to hide the loading animation as soon as all the background tasks are finished
getUserFacebookData()
to get Facebook-user data
uploadUserFacebookDataToServer()
to upload the Facebook-user data to the server (and perform tasks with them).
What I want to perform:
Show up the loading animation: showLoadingAnimation()
Get the user data from Facebook: getFacebookData()
Wait until these data are being downloaded
As soon as the Facebook-user data are being download, upload these data to the server: uploadUserFacebookDataToServer()
Wait untile these data are being uploaded
Hide the loading animation: hideLoadingAnimation()
Now my problem is, that I don't know how to solve this problem. I know, that I should use sync and/or async tasks, GCD... But I don't know how, and I can't find a proper guide to it.
Could someone explain it to me through these functions?
Thanks!
UPDATE:
Thank you, Zhi-Wei Cai, that was the kind of answer what I was hoping for.
Now it seems to work, the calling order is OK,
but now the problem is the same as the beginning:
uploadUserFacebookDataToServer()
doesn't wait until
getUserFacebookData
downloads the user data from Facebook, that's why it won't be able to work with the necessary data given back from
getUserFacebookData
Any idea? Is there anything to do with dispatch?
UPDATE 2:
As you requested, here are the fuctions. I hope, with these information you can help me to solve this problem and to understand this whole process.
func getFacebookUserData(completionHandler: () -> Void)
{
println("getFacebookUserData")
let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: nil)
graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in
if ((error) != nil)
{
// Process error
println("Error: \(error)")
}
else
{
let userID : NSString = result.valueForKey("id") as NSString!
var defaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(userID, forKey: "settings_facebookID")
self.facebookID_fromSettings = userID
}
})
and
func getObjectIDfromFacebookID(completionHandler: () -> Void)
{
println("getObjectIDfromFacebookID")
var query = PFQuery(className:"users")
query.whereKey("facebookID", equalTo:facebookID_fromSettings)
println("getObjectIDfromFacebookID: facebookID: " + facebookID_fromSettings)
query.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
// The find succeeded.
println("Successfully retrieved \(objects!.count) scores.")
// Do something with the found objects
if (objects!.count == 0) {
// New user, registering
println("New user, registering")
}
else
{
//User is already regsitered, reading out objectID
println("User is already regsitered, reading out objectID")
}
if let objects = objects as? [PFObject] {
for object in objects {
println("objectID: " + object.objectId)
var objectID: String = object.objectId
println(objectID)
var defaults: NSUserDefaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(objectID, forKey: "settings_objectID")
}
}
}
}
completionHandler()
}
So the first function gets the facebookID from the FB-server, but this process takes time, it won't give a result immediately. The second function should work with this data, that's why it should "wait" until the first gives back the requested data.
I can solve this problem by building these 2 fuctions together in one, but that's "not elegant", and I also would like to use this (sync/async dispatch) method in other parts of the project,
Thanks for trying to help me!
You can use completion handlers:
func showLoadingAnimation() {
self.getUserFacebookData({ () -> Void in
self.uploadUserFacebookDataToServer({ () -> Void in
self.hideLoadingAnimation()
})
})
}
func getUserFacebookData(completionHandler: () -> Void) {
println("getUserFacebookData")
completionHandler()
}
func uploadUserFacebookDataToServer(completionHandler: () -> Void) {
println("uploadUserFacebookDataToServer")
completionHandler()
}
func hideLoadingAnimation() {
println("hideLoadingAnimation")
}
Once showLoadingAnimation() is called, the rest will be done asynchronously.
Reference: https://developer.apple.com/library/ios/featuredarticles/Short_Practical_Guide_Blocks/
[EDIT] Use dispatch_group_t
check following code
Step 1: showLoadingAnimation()
Step 2: dispatch_group_t faceBookService = dispatch_group_create();
Step 3:dispatch_group_async_enter(faceBookService,queue,^{
getUserFacebookData()
// The below given line should be inside completion handler or after the above task has finished
dispatch_group_leave(faceBookService);
});
Step 4:dispatch_group_async_enter(faceBookService,queue,^{
uploadUserFacebookDataToServer()
// The below given line should be inside completion handler or after the above task has finished
dispatch_group_leave(faceBookService);
});
Step 5:dispatch_group_notify(faceBookService,dispatch_get_main_queue(),^{
//Called after finishing both tasks.
hideLoadingAnimation()
});